Eu faço assim para um banco de dados chamado foo_db:
create database foo_db;
create user foo_user identified by 'foo_password';
grant all on foo_db.* to 'foo_user'@'%';
flush privileges;
create database foo_db;
create user foo_user identified by 'foo_password';
grant all on foo_db.* to 'foo_user'@'%';
flush privileges;